Trim the stems from the fennel and peel the bottoms. Chop the fronds and reserve. Chop the bulb and cook it in boiling salted water for 2 minutes. Drain.

Melt the butter in a medium saucepan over medium-low heat. Add the onion; cook until lightly golden, about 5 minutes. Add the tomatoes, thyme, broth and drained chopped fennel. Cook, covered, over low heat until tender, about 25 minutes.

Remove the cover from the saucepan and cook until any excess liquid has evaporated. Add the Pernod, raise the heat slightly , and cook 2 minutes. Add the sea salt and pepper to taste and sprinkle with the chopped fennel fronds. Serves 4.